As smartphones are widely used and Access Points (APs) (WLAN repeaters) are increasingly installed in recent years, there is an increasing demand for an indoor location recognition service. In reality, potential utility that can be expected by the indoor location recognition system has been recognized over the past few years, and there have been various attempts to realize an Indoor Positioning System (IPS) having widespread availability and high accuracy. In particular, the WLAN fingerprint-based technique is widely used because of its high accuracy. However, this technique requires construction of a radio map, which is a DB containing collected WLAN signals and information on locations where corresponding signals are collected.
In an indoor space where the radio map is constructed, a location recognition system is mounted in the radio map, and can easily provide location information of a mobile device having a wireless signal receiver attached thereto. The location recognition system mounted in the radio map generally finds some most similar WLAN fingerprints to the WLAN fingerprints collected by the mobile device from the radio map, and estimates a location based on information of locations where the found WLAN fingerprints were collected. Therefore, the most important work in developing the indoor location recognition systems is constructing the radio map by collecting WLAN fingerprints in indoor spaces all over the world along with information on collection locations. However, much cost and much effort are required to construct the radio map in the indoor spaces. Therefore, there is a need for an automated radio map construction technique which is improved so as to extremely save the cost and time.
There have been various attempts to reduce the cost. There is a method for constructing a radio map by driving a vehicle having a device mounted therein for collecting GPS signals and WLAN signals simultaneously, and tagging the collection points of the collected WLAN signals. In addition, there is a method for constructing a radio map using WLAN signals which are obtained along with GPS signals in a user's mobile device. However, the method of using the GPS signals as reference locations has the disadvantage that WLAN signals collected in indoor spaces are not utilized. This is because the GPS signals does not arrive in the indoor spaces. There has been an attempt to construct the radio map by automatically tagging collection points using signal information obtained by various sensors along with WLAN signals. However, this technique also requires additional costs in constructing the radio map and still has limitations in view of the availability and accuracy.